Retropie Installation on Ubuntu Server x64 18.04.1

Clyde

@johnodon said in Retropie Installation on Ubuntu Server x64 18.04.1:

makefile:1032: *** Python is not available in path. Stop.

Maybe that's because Ubuntu switched to Python 3 ex factory with 20.04. You could try to change the system's standard alternative for python, see here for instructions.

johnodon

@Clyde said in Retropie Installation on Ubuntu Server x64 18.04.1:

@johnodon said in Retropie Installation on Ubuntu Server x64 18.04.1:

makefile:1032: *** Python is not available in path. Stop.

Maybe that's because Ubuntu switched to Python 3 ex factory with 20.04. You could try to change the system's standard alternative for python, see here for instructions.

Thanks @Clyde.

I guess the question is if this is something that needs to be accounted for in @MisterB's script or in the RP scriptmodule.

Clyde

@johnodon Absolutely. Alas, I don't know anything about scripting or Python. It's just that a friend told me about his problems (with GIMP plugins that still require P2) because of the change in Ubuntu yesterday.

johnodon

I opened an issue on @MisterB's github and he is already engaged. I'm going to perform some more testing.

etheling

@johnodon Great to hear that you got it working. Btw - after installing newer mainline kernel, I am always getting this message/error during boot up:

initramfs unpacking failed: Decoding failed

It appears it's caused by this bug, and I can make the message go away by following proposed temp workaround (tl;dr; change LZ4->GZIP in /etc/initramfs-tools/initramfs.confand run update-initramfs -c).

edit #1: mentioning this as it introduces a visual distraction by 'breaking' the clean Plymouth themed boot up into ES as the error message is shown.

Clyde

@etheling said in Retropie Installation on Ubuntu Server x64 18.04.1:

It appears it's caused by this bug

Reported over a year ago, importance "high", but still unassigned. 😒

edit: However, one of Canonical's staff engineers commented in April:

We currently believe that the decoding error reported in dmesg is actually harmless and has no impact on usability on the system.

Switching from lz4 to gzip compression, simply papers over the warning, without any benefits, and slows down boot.

Kernel should be fixed to correctly parse lz4 compressed initrds, or at least lower the warning, to not be user visible as an error.

So, it may be that that error doesn't cause any actual problems.

Sorry for the research spree, back to topic.

mitu

@johnodon said in Retropie Installation on Ubuntu Server x64 18.04.1:

...
Setting up swapspace version 1, size = 5 GiB (5321519104 bytes)
no label, UUID=a9d782a2-e629-4f3d-927e-4d78db137903
swapon: /home/pi/RetroPie-Setup/tmp/swap: swapon failed: Invalid argument
GCC 9 detected
makefile:1032: *** Python is not available in path.  Stop.
strip: 'mame64': No such file
Removing additional swap
```

The should be fixed in the RetroPie module.

johnodon

@mitu said in Retropie Installation on Ubuntu Server x64 18.04.1:

The should be fixed in the RetroPie module.

EDIT: Are you saying it is fixed or it will be fixed? I don't see any commits or PRs that are recent enough.

Thanks @mitu . I'll give it another go.

John

mitu

@johnodon Uh, I said should, as in we should probably fix this. Thus far, nothing changed.

johnodon

@mitu said in Retropie Installation on Ubuntu Server x64 18.04.1:

@johnodon Uh, I said should, as in we should probably fix this. Thus far, nothing changed.

LOL...I just updated my post above and saw your reply just pop up. :)

I read your initial reply as "this should be fixed" as in already fixed.

johnodon

@mitu said in Retropie Installation on Ubuntu Server x64 18.04.1:

@johnodon Uh, I said should, as in we should probably fix this. Thus far, nothing changed.

Issue submitted on GH.

etheling

So, it may be that that error doesn't cause any actual problems.

Visual problem with RetroPie is that it 'breaks' the clean Plymouth themed boot up into ES as the error message pops up.

johnodon

@Clyde said in Retropie Installation on Ubuntu Server x64 18.04.1:

@johnodon said in Retropie Installation on Ubuntu Server x64 18.04.1:

makefile:1032: *** Python is not available in path. Stop.

Maybe that's because Ubuntu switched to Python 3 ex factory with 20.04. You could try to change the system's standard alternative for python, see here for instructions.

Just reporting back that this worked perfectly.

Clyde

@etheling Maybe some of the tips for hiding the boot texts can help? (Ubuntu doesn't have a /boot/cmdline.txt, but most of those options are either kernel parameters for GRUB, or should be applicable in some other config files.)

johnodon

@johnodon said in Retropie Installation on Ubuntu Server x64 18.04.1:

@mitu said in Retropie Installation on Ubuntu Server x64 18.04.1:

@johnodon Uh, I said should, as in we should probably fix this. Thus far, nothing changed.

Issue submitted on GH.

Looks like @mitu submitted a PR and it was merged. I'll test this today.

https://github.com/RetroPie/RetroPie-Setup/pull/3229

John

Clyde

@johnodon @mitu Ahh, that's the synergy which I love about open source communies. Thank both of you!

etheling

@Clyde you sure sent me down the rabbit hole here! :)

It appears that when using latest stable mainline kernel 5.8.10 (as of 2020/09) it no longer gives out initramfs unpacking failed: Decoding failed error. So finding working kernel may be the path of least resistance here. Or spending ~1s longer booting when using gzip compression.

That said, based on info in that Ubuntu bug report it looks like 'initramfs unpacking...' error is sent as KERN_CRIT (loglevel=2), so I thought I'll be done with it by simply
dropping kernel loglevel to KERN_EMERG (loglevel=0). And sure enough, it's hidden, but after boot I thought I'll check that the error is still in kernel logs and that it got hidden and that loglevel got properly set:

$ pi@retropie ~ $ dmesg | grep -i 'initramfs unpacking'
[    0.834312] Initramfs unpacking failed: Decoding failed
pi@retropie ~ $ uname -a
Linux retropie 5.7.19-050719-generic #202008270830 SMP Thu Aug 27 08:35:40 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
pi@retropie ~ $ cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-5.7.19-050719-generic root=UUID=639b8c73-24be-4c14-858b-4e4c017dcc8e ro loglevel=0 splash vt.global_cursor_default=0 vt.handoff=7
$ cat /proc/sys/kernel/printk
4       4       1       7

All as expected, except that kernel is now back to KERN_WARNING (loglevel=4).

It turns out that modern Linux distributions set kernel log level during boot to distro specific defaults. In Ubuntu this is controlled by /etc/sysctl.d/10-console-messages.conf where kernel.printk = 4 4 1 7is set (on Raspberry OS / Raspbian these are /etc/sysctl.d/98-rpi.conf, kernel.printk = 3 4 1 3). In 'old' days, with pre-systemd Linuxes, which is when I looked at this direction last time, when you set loglevel boot parameter, that's what you had when the OS was up. So this was a bit confusing at first.

This also lead me to look into boot parameters. As it turns out, quiet is actually a shorthand for loglevel=4 (KERN_WARNING). Both Ubuntu (source code) and Raspberry Pi documentation state this. Thus quiet and loglevel= ~~should never be used at the same time to boot the kernel~~ since one or the other will override the other. Also note that while Ubuntu defaults to 'quiet' (loglevel=4) log level after boot, Raspberry OS switches to loglevel=3 after boot (e.g. lower than quiet).

edit #2: alas, quiet appears to be more than just a shorthand; e.g. if used, it's made available as an environment variable to /usr/share/initramfs-tools/init and other scripts which will limit their output when 'quiet' is specified. So the 'correct' way to limit output during boot is that both quiet and log_level have to be used, in exactly that order (e.g. quiet first so it get's set, and then loglevel= to override the loglevel=4 set by quiet).

So it looks like most documentation online is ~~plain wrong or~~ at least misleading regarding silently booting Linux and recommends mixed use of 'quiet' and 'loglevel' without consideration that their order matters, or does not account for the fact that quiet really means loglevel=4. Or mention that Linuxes will during boot switch to distro specific loglevels, which for example in case of Raspbian OS is more silent than 'quiet' boot parameter.

Based on this, a couple of recommendations:

Update RetroPie documentation to mention that with quiet and loglevel, order matters. Was: to not recommend using quiet (loglevel=4), and only recommend to use loglevel=3 (which is also where RaspberryOS will switch after boot). And maybe link to RaspberryPi docs about 'quiet' as a reminder to avoid future confusion about the matter.
~~Update Ubuntu setup script to use both 'quiet' and 'loglevel=0' in that order instead of 'quiet' @MisterB to actually be silent~~ edit #3: after some consideration; maybe just apply quiet - e.g. no changes needed (as it is silent enough alread, unless using a buggy kernel for which workarounds exist)
Consider if for truly silent system, also /etc/sysctl.d/{10-console-messages|98-rpi}.conf' should be changed to set lower loglevels?
Consider if loglevel=0 (or some other loglevel < 4) is a way to go all around? After all this is console loglevel, and everything will still get written to kernel logs if needed for debugging (regardless of the fact that messages to console would get suppressed).

Personally for my RetroPie installation I am going with loglevel=0 for both boot and post-boot (I set /etc/sysctl.d/{10-console-messages|98-rpi}.conf to kernel.printk = 0 4 0 7). That said, I don't think I've fully thought out what negative impacts this might have so I have some hesitation to yet recommend this as a go-to tactic to silence the system. Or if the kernel.printk should be set to e.g. '0 4 8 7' instead - especially I am not confident about 3rd parameter (minimum_console_loglevel) and what it really does, or even if loglevel=0 is really valid, and I'm not ready to read the kernel source yet. Food for thought though.

Fun times.

edit: added link to /proc/sys/kernel/printk documentation.

edit: see edit#2 above and strikeouts (e.g. quiet appears to do more than just set the log level after all).

Clyde

@etheling said in Retropie Installation on Ubuntu Server x64 18.04.1:

@Clyde you sure sent me down the rabbit hole here! :)

It seems so, my pleasure. What a hell of an elaborate report! 🧐

So finding working kernel may be the path of least resistance here. Or spending ~1s longer booting when using gzip compression.

Decisions, decisions … 😉

As it turns out, quiet is actually a shorthand for loglevel=4 (KERN_WARNING).

Even after more than 13 years of using Linux as my main OS on many machines, I didn't know that, thanks!

Raspberry OS switches to loglevel=3 after boot (e.g. lower than quiet).

Or quieter than quiet. 😎

So it looks like most documentation online is plain wrong or at least misleading

As it is, sadly, for many documentations ans how-tos on the net, which are either outdated and/or circulate wild combinations from other sources. After all, technical information tends to not aging well and has to be maintained, which requires ongoing time, effort, and dedication.

Based on this, a couple of recommendations:

Which may be better placed in a new thread, preferably in https://retropie.org.uk/forum/category/10/ideas-and-development, or even as issues for the corresponding files on Github?

Fun times.

Indeed. Thanks for all the effort, as OCD-driven it may have been. 🤓

etheling

@Clyde Thanks! Although it looks like I jumped the gun a bit (see Edit #2 / strikethroughs in previous post). E.g. I just realized that I still got console message(s) during boot after removing quiet and adding loglevel=0:

Begin: Loading essential drivers ... done
...

Which comes from here:

pi@retropie ~ $ grep -ri 'essential drivers' /usr
/usr/share/initramfs-tools/init:[ "$quiet" != "y" ] && log_begin_msg "Loading essential drivers"

So the 'correct' way appears to be after all to use quiet followed by loglevel= for a desired loglevel to override loglevel=4 set by quiet. I should have just read the Archlinux documentation for silent boot right a way! ;-)

Which may be better placed in a new thread, preferably in https://retropie.org.uk/forum/category/10/ideas-and-development, or even as issues for the corresponding files on Github?

I'll start a new thread later. I think this is not as clear cut as I initially thought it was, so I think some discussion might be useful before creating an issue/PR.

MisterB

Lots of great discussion here, so I figured I'd check in. Just wanted to acknowledge that I am working on script updates now, and hope to have something published in the next few days. In addition to incorporating some of the great ideas above into the 'core' install script, I also plan to allow for pre and post-install script folders, which will allow for further customization. My vision is to include a library of optional add-on script files in the repository, which can then be copied/moved/linked into these pre/post folders and be automatically executed by the master script. Still playing with some implementation options.